Biodistribution of ultra small superparamagnetic iron oxide nanoparticles in BALB mice

Recently ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (NPs) have been widely used for medical applications. One of their important applications is using these particles as MRI contrast agent. While various research works have been done about MRI application of USPIOs, there is limited research about their uptakes in various organs. The aim of this study was to evaluate the biodistribution of dextran coated iron oxide NPs labelled with ^99mTc in various organs via intravenous injection in Balb/c mice. The magnetite NPs were dispersed in phosphate buffered saline and SnCl₂ which was used as a reduction reagent. Subsequently, the radioisotope ^99mTc was mixed directly into the reaction solution. The labeling efficiency of USPIOs labeled with ^99mTc, was above 99 %. Sixty mice were sacrificed at 12 different time points (From 1 min to 48 h post injections; five mice at each time). The percentage of injected dose per gram of each organ was measured by direct counting for 19 harvested organs of the mice. The biodistribution of ^99mTc-USPIO in Balb/c mice showed dramatic uptake in reticuloendothelial system. Accordingly, about 75 percent of injected dose was found in spleen and liver at 15 min post injection. More than 24 % of the NPs remain in liver after 48 h post-injection and their clearance is so fast in other organs. The results suggest that USPIOs as characterized in our study can be potentially used as contrast agent in MR Imaging, distributing reticuloendothelial system specially spleen and liver.     

Substitution Effect in NICS Values in Tropylium Ion Derivatives: An Ab Initio Study

Hartree–Fock (HF) and hybrid density functional theory (B3LYP) calculations were performed on tropylium ion and 19 of its mono- and diheteroatomic derivatives. The aromaticity in this class of compounds is evaluated based on the nucleus independent chemical shift (NICS) values. The NICS values are calculated at the center of the rings NICS (0) and at 1Å above the molecular plane NICS (1). The geometry optimization and NICS calculations were carried out at the HF/6–311+G?? and at the B3LYP/6–311+G (2d, p) density functional level, respectively. These calculations in the effects of heteroatoms such as N, B, P, and Si are considered on aromaticity, molecular properties, NICS values, and structural parameters.     

Highly Efficient Synthesis of Substituted Benzenes in the Presence of B(HSO4)3 as a New and Reusable Catalyst Under Solvent-Free Conditions

A highly efficient and simple procedure for the synthesis of substituted benzenes is described. A broad range of ketones (alkyl–aryl ketones and cyclic ketones) were condensed via a cyclotrimerization reaction in the presence of catalytic amounts of boron sulfonic acid [B(HSO₄)₃], a new, highly efficient, and reusable catalyst, under solvent-free conditions. All reactions completed in short times without formation of any by-products. The catalyst was recovered and reused successfully for 15 cycles of the reaction.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Nontrivial tensile behavior of rutile TiO<Subscript>2</Subscript> nanowires: a molecular dynamics study

In this paper, we study the tensile behavior of cylindrical rutile TiO₂ nanowires, employing molecular dynamics (MD) simulation technique. The third-generation charge optimized many-body (COMB3) has been used for interatomic potential modeling. The influence of temperature and nanowire diameter on Young’s modulus is investigated. Our simulations exhibit the anisotropic behavior of Young’s modulus as a function of diameter for different crystallographic orientations. Although our results are in good accord with the existing results in [1 0 0] direction, Young’s modulus adds up monotonically with increasing the cross-sectional diameter of nanowire in [0 0 1] direction. It is found that Young’s modulus of the nanowires are lower (higher) than the bulk value for [0 0 1] ([1 0 0]) direction. Furthermore, simulation results also indicate that Young’s modulus of rutile TiO₂ nanowire increases as a function of temperature for a given diameter, unexpectedly. The obtained results may be useful in the field of nanotechnology for optimizing mechanical performance to gain specific applications.